Manufacture of laminated safety glass



June 27, 1939. G. B. WATKINS ET AL MANUFACTURE OF LAMINATED SAFETY GLASSFile'd May 9, 1956 2 Sheets-Sheet l WWI/MA June. 27, 1939.

s. B. WATKINS El AL 2,163,648

MANUFACTURE OF LAMINATED SAFETY GLASS Filed May 9, 1956 2 Sheets-Sheet 2fl///// l gwuovvto w GEORGE 5. WATKINS. 041/0 H. ooaw/LL/s rained June27, 1939 UNITED STATES mnnmoroae or LAMINATED SAFETY GLASS "George B.Watkins and David H. Goodwillie, Toledo, Ohio, assignors toLibbey-Owens-Ford Glass Company, Toledo, Ohio, a corporation of OhioApplication May 9, 1936, Serial No. 78,740

(Claims (01. 49-81) This invention relates to the manufacture oflaminatedsafety glass.

In carrying out the invention, a sheet of synthetic resin plastic isinterposed between two 5 sheets of glassto form a fsandwich which isthen subjected to a pressing operation at suitable temperatures toeifect the bonding of the laminations to form a composite structure. Theresin plastic used may consist of properly plasticized i Butylvar,Formvar, Alvar, the acrylic acid ester type of resin, vinyl acetate,etc. found that a resin plastic, when bonded between glass sheets, willoffer greater resistance to impact at high, medium, and low temperaturesnormally encountered in actual use than will similar laminated glasshaving a cellulosic derivative plastic bonded between the glass sheets.It is characteristic of the cellulosic derivative plastics to becomerelatively more brittle at the lower temzo peratures and it has been anaim in the art for some time to avoid this tendency toward brittleness,r

The object of the present invention is the provisionof an improvedapparatus for eifecting the 25 bonding together of the laminations in arapid,

eflicient, and economical manner. More particularly, the'inventioncomprehends the bonding together of the laminations in a continuousmanner by means of a roll type of press including a plu- 30 rality ofpairs of pressing rolls between which the assembled laminations arepassed, the said rolls being of such a size and so spaced that theyprevent any substantial flexing or bending of the glass sheets duringthe pressing operation.

36 The amount of pressure applied to the laminations as well as thetemperature thereof is varied during pressing in such a manner as tofirst exclude air and non-condensable gases from between thelaminations, after which permanent 40 adhesion is obtained.

In the drawings wherein like numerals are employed to designate likeparts throughout the same:

Fig. 1 is a diagrammatic sectional view showing 45 two sheets of glassand a layer of plastic in proper superimposed relationship;

Fig. 2 is a longitudinal vertical sectional view of the apparatus,employed for bonding the as- 50 sembled laminations;

Fig. 3 is a side elevation of a portion of the apparatus, partially insection, showing the means for controlling the pressure of the rolls;

Fig. 4 is a vertical sectional view taken substan- 55 tially on line 44of Fig. 2; and

It has been Fig. 5 is a sectional view of the finished laminated sheet.

' Referring first to Fig. 1, there is illustrated a sheet I of asuitable synthetic resin plastic such as, for example, Alvar, Formyar,or Butylvar type 5 of resin disposed between the two sheets of glass Hand I2, The sheet I0 is a preformed layer of plastic including anypreferred and selected amount of plasticizer, and it will be understoodthat adhesives or other bond inducing mediums can be employed to promotethe requisite bond between the laminations or not, as desired.

After the laminations have been arranged in properly assembledrelationship, to form a sandwich, the said sandwich is subjected to thede sired temperatures and pressures to unite the laminations and thusform a unitary structure. The pressing of the sandwiches is adapted tobe accomplished in a continuous manner and by means of a roll type ofpress, such as shown in Fig. 2, wherein the Sandwiches [3 are passedhoriz ontally between a series of pairs of horizontally aligned rolls l4and I5 preferably of rubber or rubber composition and enclosed in ahousing l6.

One of the difliculties experienced in bonding laminated glass ina'continuous manner using roll pressure has been the slight flexingaction of the glass, because of the unequal distribution of pressure onthe laminations as they pass between the rolls. When using the softerplastics, particu larly plastics made from the vinyl type of resin; suchas Formvar, Alvar, and Butylvar, there is even a greater tendency towardflexing of the glass-plastic sandwich due to the greater plasticity orlack of rigidity of the resin type of plastics. Obviously, the flexingaction is increased with increased plasticityof the plastic, withincreasing pressure on the rolls, increasing distances between rollcenters applying the'pressure, and with decreasing glass thickness used40 in preparing the glass-plastic sandwich.

We have found that it is possible to prevent any flexing or bending ofthe glass sheets by materially reducing the diameter of the rolls and inpositioning them sufliciently close together so that they will act uponthe laminations in a manner similar to a rigid platen press. Forinstance, our work along this line indicates that rolls approximatelyone inch in diameter and spaced one-quarter inch apart will besatisfactory for continuously press-- ing resin plastic laminationsusing one-eighth inch plate glass. The softer characteristics of theresin plastics permits the molding and satisfactory bonding of theplastic-glass laminations with a pressure sufficiently low so as not toproduce undue glass.

bending or flexing of the glass plates as they pass continuously betweenthe small rolls.

One of the disadvantages inusing the smallpressing rolls, however, in apress of this kind is the actual bending of the rolls themselves,particularly in a pressing machine of substantial width such as amachine sufliciently wide to accommodate a forty-eight inch width lightof This bending of the rolls obviously creates unequal pressure withrespect to the glass sheets being pressed. To overcome this dimculty, wepropose the backing-up of the small pressing rolls It and I5 with therolls I1 and I8, the said rolls I1 and I8 contacting with rolls It and65 respectively and furnishing suflicient reinforcement to prevent thebending or distortion of the small rolls contacting the glass.

As the glass-plastic sandwich progresses between the pairs of pressingrolls It and I5, the pressure of the said rolls thereon is graduallyreduced while the temperature thereof is simultaneously increased. Thegradual lessening of p the roll pressure can be accomplished by properregulation of the rolls while the gradual increase in temperature may beeffected by spraying jets of heated liquid upon opposite surfaces of thesandwichfrom perforated pipes 59 and 20 extending transversely withinthe housing It above and beneath the rolls or in any other desiredmanner. The rolls Id and I5 at the forward end .of the housing areadapted to exert the desired maximum pressure upon thesandwich and thispressure is gradually decreased toward the exit end thereof where thedesired minimum pressure is employed. The exact pressure upon thesandwich and likewise the temperature thereof would depend upon the typeof plastic being bonded and would be such as to effect satisfactorybonding for safety glass purposes.

The mounting of the pressing and backing-up rolls is shown in Figs. 3and 4, and it will be seen that the lower pressing roll M of each pairis carried upon a shaft 2| projecting at its opposite ends through theside walls of the housing I6 and journaled at each end in a bearingblock 22 mounted in a vertical standard 23, while the correspondingupper roll I5 is carried upon a shaft 2d also projecting at oppositeends beyond the housing and journaled at each end in a bearing block 25slidably mounted in the standard 23 above bearing block 22. Arrangedbetween the bearing blocks 22 and 25 is a wedge 26 which limits themovement of the said blocks and consequently the pressing rolls It andI5 toward one another.

The backing-up roll H for each pressing roll It is carried by a shaft 21journaled in bearing blocks 28 positioned beneath bearing blocks 22,while the backing-up roll I8 for the pressing roll I5 is carried by ashaft 29 journaled in bearing blocks 30 located above bearing blocks 25.

The upper bearing blocks 36 are each provided with a vertical rod 3which projects upwardly through the bottom of a cylinder 32 supportedupon the top of the respective standard 23 and fixed to the rod 3|within the cylinder is a piston 33. Extending longitudinally at eachside of the housing I5 is a supply pipe 36 containing either liquid orair under pressure and which is in communication with each of thecylinders 32 at the corresponding side of the housing by means of a,pipe 35 within which is disposed avalve 36 provided to control theamount of compressed air or liquid supplied to the cylinder. With thisarrangement, the pressure exerted by the individual pairs of pressingrolls Hi and I5 upon the laminations can be independently controlled.

Extending longitudinally at one side of the housing I6, adjacent the topthereof, is a pair of spaced parallel supply pipes 37 and 38 with whicheach perforated transverse pipe I9 communicates through a mixing valve38. Also extending longitudinally of the housing, adjacent the bottomthereof, is a pair of similar supply pipes M and M with which theperforated transverse pipes 20 communicate through mixing valves 52. Thepipes .31 and ii! are adapted to be supplied with a suitable heatedliquid such as water while pipes 38 and AI are adapted to receive asuitable cooling liquid, and by proper adjustment of the mixing valves39 and d2, liquid of the desired temperature can be fed to thetransverse pipes I9 and 20 from which it is sprayed upon oppositesurfaces of the sandwiches IBas-they pass between the'rolls. The pipesI9 and 20 are so positioned that the liquid sprays therefrom passbetween the adjacent pressing and backing-up rolls as clearly shown inFig. 2.

The bottom of the housing I6 is inclined down- ;wardly from both ends tothe central outlet 63 connected to a reservoir 64. Positioned atopposite sides of the reservoir are the two heat exchangers 35 and Q6and the liquid .is adapted to be pumped from the reservoir through thesaid heat exchangers by the motors 41 and 48 respectively. The liquid,in passing through the heat exchanger 65, is adapted to be heated andpasses therefrom through a pipe 69 which communicates with both of thesupply pipes 37 and d0 while the liquid passing through the heatexchanger 65 is adapted to be cooled and passes therefrom through apipe. 50 which communicates'with both of the supply pipes 38 and ll.Thus, it will be seen that heated liquid is being continuously passedthrough pipes 31 and 40 and cooling liquid through pipes 38 and 4| sothat by proper control of the mixing valves 39v and &2, liquid of thedesired temperature can be supplied to the transverse perforated pipesI9 and 20.

To press the sandwiches I3, they are first placed upon a conveyor 5|from which they are passed between a pair of nipping rolls 52 and 53 andthence into the housing l5 and between the pressure rolls I4 and I5which are positively driven in any suitable manner to advance thesandwiches through the said housing. In view of the fact that the resinplastics above set forth might be tacky at normal temperatures, thefirst pair of rolls or group of rolls are adjusted to exert the desiredmaximum pressure upon the sandwiches and during this pressing treatmentthe sandwiches are either at normal room temperature or alowertemperature, with the result that air and non-condensable gaseswill be swept from between the glass-plastic laminations. Then, as thesandwiches progress between the rolls, the temperature thereof isgradually raised to the point necessary for bonding the laminations. Asthe temperature of the resin plastics is raised, their softness orflowability increases; and it is therefore desirable to decrease thepressure with increase in temperature to prevent flowing or extruding ofthe plastic and therefore pinching of the laminations around the edgesthereof. As the sandwiches issue from the housing, they pass between apair of rolls 5% and 55 onto the receiving conveyor 56.

Due to the nature of the synthetic resin plastics above set forth, it isnot necessary to undercut and seal the marginal portions of thecomposited glass, which is shown in Fig. 5,' because it has been foundthat weathering does not adversely affect either the plastic or the bondbetween the plastic and glass.

"We claim:

1. Apparatus for use in the manufacture of laminated safety glassincluding a plurality of pairs of pressing rolls'between which theassembled laminations to be bonded are adapted to be passed, abacking-up roll engaging each pressure roll to prevent bending thereof,and means for heating the laminations as they pass between the rolls.

2. Apparatus for use in the manufacture of laminated safety glassincluding a plurality of pairs of pressing rolls between which theassembled laminations to be bonded are adapted to be passed, abacking-up roll engaging each pressure roll to prevent bending thereof,means for independently controlling the pressure exerted by each pair ofpressing rolls upon the laminations, and means for heating thelaminations as they pass between the rolls. I

3. Apparatus for use in the manufacture of laminated safety glassincluding a plurality of pairs of pressing rolls between which theassembled laminations to be bonded are adapted to be passed, abacking-up roll engaging each pressure roll to prevent bending thereof,means for cooling the laminations at the beginning of thepressingoperation, and means for subsequently heating the laminations as thepressing operation continues.

4. Apparatus for use in the manufacture of laminated safety glassincluding a plurality of pairs of pressing rolls between which theassembled laminations-to be bonded are adapted to be passed, abacking-up roll engaging each pressure roll to prevent bending thereof,means for independently controlling the pressure exerted by each pair ofpressing rolls upon the laminations, means for cooling the laminationsat the beginning of the pressing operation, and means for subsequentlyheating the laminations as the pressing operation continues.

5. Apparatus for use in the manufacture of laminated safety glassincluding a plurality of pairs of pressing rolls between which theassembled laminations to be bonded are adapted to be passed, abacking-up roll engaging each pressure roll to prevent bending thereof,a housing enclosing said rolls, means arranged in the forward end of thehousing for cooling the laminations, and means arranged in the oppositeend of said housing for heating the said laminations.

6. Apparatus for use in the manufacture of laminated safety glassincluding a plurality of pairs of pressing rolls between which theassembled laminations to be bonded are adapted to be passed, abacking-up roll engaging each pres- .sure roll to prevent bendingthereof, means for independently controlling the pressure exerted byeach pair of pressing roll's upon the laminations, a housing enclosingsaid rolls, means arranged in the forward end of the housing for coolingthe laminations, and means arranged in the opposite end of said housingfor heating the said laminations.

7. Apparatus for use in the manufacture of laminated safety glassincluding a plurality of pairs of pressing rolls between which theassembled laminations to be bonded are adapted to be passed; abacking-up roll engaging each pressure roll to prevent bending thereof,means for independently controlling the pressure exerted by each pair ofpressing rolls upon the laminations,

a housing enclosing said rolls, means arranged in the forward end of thehousing for cooling the laminations, and means arranged in the oppositeend of said housing for heating the said laminations, said cooling meanshaving a gradually reducing cooling effect upon the laminations and theheating means having a gradually increasing heating eifect thereon asthe said laminations pass through the said housing.

GEORGE B. WATKINS. DAVID H. GOODWILLIEL

